Proton relaxivity temperature dependence

D.E. Woessner B.S. Snowden, Jr. (1967). J. Chem. Phys., 47, 378-381. Proton spin-lattice relaxation temperature dependence in ammonium bromide. 

The diffusion of protons and deuterons in a single crystal was studied by means of infra-red absorption. The chemical diffusion coefficient of protons was deduced from the relaxation time of the absorption intensity upon replacing deuterons with protons. The temperature dependence of the chemical diffusion coefficient of protons was described by ... 

If the amount of the sample is sufficient, then the carbon skeleton is best traced out from the two-dimensional INADEQUATE experiment. If the absolute configuration of particular C atoms is needed, the empirical applications of diastereotopism and chiral shift reagents are useful (Section 2.4). Anisotropic and ring current effects supply information about conformation and aromaticity (Section 2.5), and pH effects can indicate the site of protonation (problem 24). Temperature-dependent NMR spectra and C spin-lattice relaxation times (Section 2.6) provide insight into molecular dynamics (problems 13 and 14). 

Fig. 5. Temperature dependence of the proton relaxivity (20 MHz) for Na[GdD0TA(H20)] (top) and [GdD0TAM(H20)]tfl3 (bottom) and individual contributions of the inner and outer sphere mechanisms.

Temperature dependence proton relaxivity 188 relaxation rate 144-5 Temperature-sensitive contrast agents 218-19 Th -" 368 Ti "" 347 Tilt angle 242 Time constant 14 Time correlation functions 76 Time-dependent mechanism 14 Time-dependent perturbation methods 23 Time-dependent perturbation theory 45-8 Titanium(III) 115,134-5,161 TPEN 224 TPPS 219... 

Figure 8. Temperature and concentration dependence of the solvent proton-solvent proton relaxation rate (%),20% (O), 10% (X), 0%.

This study is similar to those previously done by Derbyshire and Duff (20) and Nystrom et al. (21) who studied water swellable gels. However, in the first of these, the use of proton NMR complicated the relaxation data because of proton-proton coupling. Furthermore, their study focused on the freezing (or non-freezing) of water which also complicated matters. In the present study, we are always well above the freezing point of toluene so that one need not worry about the freezing of the solvent. The study by Nystrom et al. (21) used deuterium NMR of D2O, but an unusual temperature dependence was observed, possibly due to the exchange of the protons or deuterons. Our present data are not complicated... 

Figure 1. Temperature dependence of proton relaxation times of cyclic hydrocarbons (C Ht, C Hs, C flio, CqHi2) adsorbed on NaY. Pore filling factor 0 = 0.8.

Figure 3. Temperature dependence of proton relaxation time Ti of water in NaPtY. Pore filling factor 6 0.8. Pretreatment procedure for 20 hours at 100° Ifi0°C. For comparison the results for NaY without platinum are also plotted.

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